The home’s exterior walls and roof should be watertight. Problems with water intrusion will likely determine how long your manufactured home survives. Leaks in the roof, walls, and foundation that admit rain water are important causes of mold, rot, and other material deterioration. Ice dams, formed by snow melting and refreezing on the edge of the roof, can force water underneath shingles and into the attic and upper walls.
Many mobile homes have no eaves and so the walls are exposed to rainwater from the roof. The seam around windows’ perimeters and their screw holes can leak water. Roof leaks most often occur at penetrations and the roof’s edge. Leaks through the roof and walls can be difficult to find because wetness can result from either roof or wall leakage or from condensation inside the roof or wall cavity. Condensation, in fact, is often mistaken for roof leakage.
Plumbing leaks are also important sources of water leakage. Leaks in water supply and drain pipes are relatively easy to find and should be fixed as soon as they are discovered.
Poor site drainage encourages seepage through skirting. Reduce water seepage with drainage ditches, gravel, perimeter water barriers, and foundation waterproofing.
The home site should be planned to keep rain water, ground water, and irrigation water away from the skirting and crawl space. The ground near the home should slope to drain away water. Employ rain gutters and regrade the site, if necessary, to carry water off the roof and away from the foundation. In areas where surface water must flow near a building, cap the ground next to the home with impermeable clay or concrete.
You can learn more about mobile home retrofitting and maintenance in my by book, Your Mobile Home: Energy and Repair Guide for Manufactured Housing.